Combustion engines, including gasoline spark-ignited engines, diesel compression ignition engines, gaseous fuel engines, and still others, operate generally by producing a controlled combustion reaction within a cylinder which drives a piston to rotate a crankshaft. This basic technique has been used to operate engines with traditional fuels such as gasoline or diesel for well over a century. Emissions concerns, price and supply concerns, amongst others, have led to increased interest and exploitation of alternative engine fuels such as natural gas, hydrogen, landfill gas, and biogas. These fuels typically are used at a higher stoichiometric air-to-fuel ratio, meaning so-called “lean” fuel/air mixtures, or mixtures having an equivalence ratio less than 1, are common. A traditional combustion engine ignition strategy that relies on spark ignition or compression ignition may fail to properly ignite such mixtures resulting in engine knock or other problems.
Use of a prechamber ignition device can address these issues by igniting a fuel/air mixture in a prechamber before delivering jets of hot combustion gases to the combustion chamber to locally raise temperature and pressure to an ignition threshold, resulting in a hotter, more uniform, and more robust combustion reaction as compared to other techniques. Typically, a prechamber device is deployed for use in an engine as part of a prechamber assembly, which is often constructed of a base formed of cast iron or steel, and the prechamber device coupled thereto. The prechamber device is typically formed of materials well-suited to withstanding regular and intense combustion reactions, such as certain alloys available under the tradename Inconel®.
While the use of a prechamber device provides certain advantages, prechamber devices can also require periodic replacement as the harsh conditions presented by combustion reactions within the prechamber, and other factors, may result in production of corrosion on or within the device. Corrosion of the outlets through which gases from the prechamber are conveyed to the cylinder can ultimately affect combustion performance of the engine amongst other things.
One attempt at removing corrosion to extend the life of a prechamber is disclosed in U.S. Pat. No. 9,371,771 to Lee et al. (“Lee”). Lee discloses a prechamber assembly for gasoline engines having removable and replaceable components, allowing for damaged or corroded parts to be repaired or replaced individually rather than the assembly as a whole. While this and other solutions may extend the life of a prechamber device in certain engine applications, such concepts may be less well suited for other engine applications or engine types, which can involve harsher operating conditions in certain respects. Accordingly, there remains ample room for improvement in this field.